GAITHERSBURG — Gaithersburg police have arrested a man they say sexually assaulted a woman while impersonating a police officer last month.

Thirty-nine-year-old Travis Anderson of North Potomac was arrested Thursday and charged with impersonating a police officer, sex offense and other charges, police say. He is being held in lieu of $125,000 bail.

Police say on Oct. 13, Anderson, who was operating a Crown Victoria with a spotlight and emergency equipment, stopped a female driver, sexually assaulted her and held her against her will.

When the victim asked for identification, Anderson got into his vehicle and fled the scene, police say.